Should we look for silent pulmonary embolism in patients with deep venous thrombosis?

BACKGROUND: Asymptomatic or silent pulmonary embolism (S-PE) in patients with deep vein thrombosis has been the focus of numerous publications with the objective of determining the incidence of S-PE and assessing whether its existence has any clinical or therapeutic consequences that outweigh the risks associated with the diagnostic tests performed and the increased healthcare costs. The objectives were to assess the incidence of S-PE using computed tomography angiogram (CTA), to understand the epidemiological factors that might trigger embolism, and to assess whether D-dimer (DD) predicts the existence of S-PE's. METHODS: A prospective and consecutive assessment of 103 hospitalized patients with lower limb DVT in the absence of PE symptoms, using CT scan. DD was quantified before anticoagulation. The risk factors and characteristics of the DVT were studied. A three-year follow-up assessing risk recurrence and clinical outcome was performed. RESULTS: The incidence of S-PE was 66%. In 77% of these cases, the main and lobar pulmonary arteries were affected. Iliac and femoral DVTs most often produced S-PE. ROC curve with a DD value higher than 578 ng/ml provided good sensitivity but low specificity to identify patients with S-PE. Diagnosis entailed higher hospitalization expenses. No significant recurrence rate of thrombotic events was observed in the S-PE group during the follow-up. CONCLUSIONS: The incidence of S-PE in lower-limb DVT is high, but in the absence of symptoms, diagnosis does not appear to be necessary, as there are no short- or long-term clinical or therapeutic consequences.

Variational modularity at the cell level: insights from the sperm head of the house mouse.

BACKGROUND: Modularity is an important feature in the evolvability of organisms, since it allows the occurrence of complex adaptations at every single level of biological systems. While at the cellular level the modular organization of molecular interactions has been analyzed in detail, the phenotypic modularity (or variational modularity) of cell shape remains unexplored. The mammalian spermatozoon constitutes one of the most complex and specialized cell types found in organisms. The structural heterogeneity found in the sperm head suggests an association between its inner composition, shape and specificity of function. However, little is known about the extent of the connections between these features. Taking advantage of the house mouse sperm morphology, we analyzed the variational modularity of the sperm head by testing several hypotheses related to its structural and functional organization. Because chromosomal rearrangements can affect the genotype-phenotype map of individuals and thus modify the patterns of covariation between traits, we also evaluate the effect of Robertsonian translocations on the modularity pattern of the sperm head. RESULTS: The results indicated that the house mouse sperm head is divided into three variational modules (the acrosomal, post-acrosomal and ventral spur module), which correspond to the main regions of the cytoskeletal mesh beneath the plasma membrane, i.e., the perinuclear theca. Most of the covariation is concentrated between the ventral spur and the acrosomal and post-acrosomal modules. Although the Rb fusions did not alter the main modularity pattern, they did affect the percentages of covariation between pairs of modules. CONCLUSIONS: The structural heterogeneity of the cytoskeleton is responsible for the modular organization of the sperm head shape, corroborating the role that this structure has in maintaining the cell shape. The reduction in percentages of shape covariation between pairs of modules in Rb sperms suggests that chromosomal rearrangements could induce changes in the genotype-phenotype map. Nevertheless, how these variations affect sperm fertilization success is yet to be elucidated.

Development of a new instrument for the assessment of psychological predictors of well-being and quality of life in people with HIV or AIDS.

This study aims to develop an instrument for the assessment of psychological predictors of well-being and quality of life (QoL) in people living with HIV. A four-step procedure was followed to achieve this objective. A literature review, focus group in different regions of Spain and content analysis generated a preliminary pool of 96 items. Interjudgement ratings over the items and a cognitive debriefing interview were performed to delete or review items (one omitted and 15 reviewed). The psychometric properties of the instrument were assessed in a sample of 84 HIV+. Pilot testing allowed a new wave of depuration process by empirical criteria (30 items omitted). A final pool of 63 items covering 23 facets (α from 0.53 to 0.95) of psychological predictors remained. Exploratory factorial analysis (GLS) assessing the underlying structure of the questionnaire showed a six-factor model explaining 56.5 of variance. Empirical exploratory structure revealed evidence of goodness of fit (χ(2) = 113.110, gl = 130, p > 0.05; RMSEA = 0.017; RMSEA IC90 % 0.000-0.057). This study presents the first instrument able to screen key psychological variables expected to be related to adjustment, well-being and QoL in people with HIV.

Knowledge and Prior Use of HIV Self-Testing in Madrid and Barcelona among Men Who Have Sex with Men More than One Year after Its Legal Authorization in Spain.

This study assessed the knowledge and prior use of HIV self-testing in a sample of men who have sex with men (MSM) recruited in a sexual health clinic and two community-based testing sites in Madrid and Barcelona, >12 months after its legal authorization. Between March 2019 and December 2020, we recruited 2044 MSM. Participants completed a self-administered questionnaire while waiting to be tested for HIV and other STIs. We built two Poisson regression models to assess factors associated with prior knowledge and with use. Among those who had used self-testing in the past we assessed frequency of use and several aspects related to the last testing episode. The proportion of participants that knew about the existence of self-testing and had already used it was of 26.3% and 5.1% respectively. Both, knowledge and use were independently associated with being born in Spain or other western European countries, university education and more recent HIV testing. Additionally, knowledge was associated with older age, having a more favorable economic situation, and not living sexuality in total secrecy. Use was also associated with having received money in exchange for sex. Most (69.5%) reported having self-tested once, 64.8% had self-tested <12 months ago, 63.8% self-tested alone and 71.4% acquired the kit at a pharmacy over the counter. In spite of its authorization and becoming legally available, knowledge and use of HIV self-testing remain low among MSM attending sites specialized in the diagnosis of HIV and other STIs. When designing scale-up strategies, lower levels of knowledge and use in less favored subgroups of MSM need to be factored in.

HIV pre-exposure prophylaxis (PrEP) in Spain: political and administrative situation. / Profilaxis preexposición al VIH en España: situación política y administrativa.

This study focuses on actions at the political and administrative level in Spain in relation to the implementation of pre-exposure prophylaxis (PrEP). We analysed a whole range of different formal initiatives taken by the political and administrative actors involved. The information was obtained from official public data sources. As of February 2018, PrEP had not been implemented. The decision is dependent on both state and regional governments. The Ministry of Health and some Autonomous Regions are working on different interventions, but without providing an implementation timetable. The political parties have kept a very low profile in terms of initiatives related to the implementation of PrEP. From a legal point of view, proceedings are passing back and forth with the extension of the patent. The role of intergovernmental and interdepartmental institutions is very important for the implementation of PrEP in Spain.

CX3CR1/CX3CL1 Axis Mediates Platelet-Leukocyte Adhesion to Arterial Endothelium in Younger Patients with a History of Idiopathic Deep Vein Thrombosis.

Mechanisms linking deep vein thrombosis (DVT) and subclinical atherosclerosis and risk of cardiovascular events are poorly understood. The aim of this study was to investigate the potential impact of CX3CR1/CX3CL1 axis in DVT-associated endothelial dysfunction. The study included 22 patients (age: 37.5 ± 8.2 years) with a history of idiopathic DVT and without known cardiovascular risk factors and 23 aged-matched control subjects (age: 34 ± 7.8 years). Flow cytometry was used to evaluate peripheral markers of platelet activation, leukocyte immunophenotypes and CX3CR1/CX3CL1 expression in both groups. A flow chamber assay was employed to measure leukocyte arrest under dynamic conditions. Platelet activation and the percentage of circulating CX3CR1-expressing platelets, CX3CR1-expressing platelet-bound monocytes and CD8+ lymphocytes were higher in patients with DVT than in controls. Additionally, patients with DVT had increased plasma levels of CX3CL1, soluble P-selectin and platelet factor 4/CXCL4. Interestingly, this correlated with enhanced platelet-leukocyte interaction and leukocyte adhesion to TNFα-stimulated arterial endothelial cells, which was partly dependent on endothelial CX3CL1 upregulation and increased CX3CR1 expression on platelets, monocytes and lymphocytes. In conclusion, increased CX3CR1 expression on circulating platelets may constitute a prognostic marker for long-term adverse cardiovascular events in patients with DVT. Blockade of CX3CL1/CX3CR1 axis may represent a new therapeutic strategy for the prevention of cardiovascular comorbidities associated with DVT.

Multimethod Approach to the Early Postnatal Growth of the Mandible in Mice from a Zone of Robertsonian Polymorphism.

The western European house mouse (Mus musculus domesticus) shows high karyotypic diversity owing to Robertsonian translocations. Morphometric studies conducted with adult mice suggest that karyotype evolution due to these chromosomal reorganizations entails variation in the form and the patterns of morphological covariation of the mandible. However, information is much scarcer regarding the effect of these rearrangements on the growth pattern of the mouse mandible over early postnatal ontogeny. Here we compare mandible growth from the second to the eighth week of postnatal life between two ontogenetic series of mice from wild populations, with the standard karyotype and with Robertsonian translocations respectively, reared under the same conditions. A multi-method approach is used, including bone histology analyses of mandible surfaces and cross-sections, as well as geometric morphometric analyses of mandible form. The mandibles of both standard and Robertsonian mice display growth acceleration around weaning, anteroposterior direction of bone maturation, a predominance of bone deposition fields over ontogeny, and relatively greater expansion of the posterior mandible region correlated with the ontogenetic increase in mandible size. Nevertheless, differences exist between the two mouse groups regarding the timing of histological maturation of the mandible, the localization of certain bone remodeling fields, the temporospatial patterns of morphological variation, and the organization into two main modules. The dissimilarities in the process of mandible growth between the two groups of mice become more evident around sexual maturity, and could arise from alterations that Robertsonian translocations may exert on genes involved in the bone remodeling mechanism. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Comparative postnatal histomorphogenesis of the mandible in wild and laboratory mice.

The coordinated activity of bone cells (i.e., osteoblasts and osteoclasts) during ontogeny underlies observed changes in bone growth rates (recorded in bone histology and bone microstructure) and bone remodeling patterns explaining the ontogenetic variation in bone size and shape. Histological cross-sections of the mandible in the C57BL/6J inbred mouse strain were recently examined in order to analyze the bone microstructure, as well as the directions and rates of bone growth according to the patterns of fluorescent labeling, with the aim of description of the early postnatal histomorphogenesis of this skeletal structure. Here we use the same approach to characterize the histomorphogenesis of the mandible in wild specimens of Mus musculus domesticus, from the second to the eighth week of postnatal life, for the first time. In addition, we assess the degree of similarity in this biological process between the wild specimens examined and the C57BL/6J laboratory strain. Bone microstructure data show that M. musculus domesticus and the C57BL/6J strain differ in the temporospatial pattern of histological maturation of the mandible, which particularly precludes the support of mandibular organization into the alveolar region and the ascending ramus modules at the histological level in M. musculus domesticus. The patterns of fluorescent labeling reveal that the mandible of the wild mice exhibits temporospatial differences in the remodeling pattern, as well as higher growth rates particularly after weaning, compared to the laboratory mice. Since the two mouse groups were reared under the same conditions, the dissimilarities found suggest the existence of differences between the groups in the genetic regulation of bone remodeling, probably as a result of their different genetic backgrounds. Despite the usual suitability of inbred mouse strains as model organisms, inferences from them to natural populations regarding bone growth should be made with caution.

Bioaccumulation of lead, mercury, and cadmium in the greater white-toothed shrew, Crocidura russula, from the Ebro Delta (NE Spain): sex- and age-dependent variation.

We quantified bioaccumulation of lead, mercury, and cadmium in bones from 105 greater white-toothed shrews (Crocidura russula) collected at the Ebro Delta, a polluted area, and the Medas Islands, a control site. Lead and mercury levels varied with site, age, and sex, although statistical significances depended on each factor. Globally, shrews from the polluted area exhibited significantly higher concentrations of Pb and Hg. Increment of Pb with age was particularly remarkable in wetland animals and was interpreted in relation to human activities, namely hunting. Unlike males, females from the Ebro Delta maintained low Hg levels, which were associated with gestation and lactation. Cadmium levels did not differ between sites, sexes, or ages. This study provides the first data on heavy metals in mammals from this wetland and suggests that C. russula is a good bioindicator of metal pollution. We concluded that sex and age may represent an important source of variation in the bioaccumulation of these metals in wild populations.

[Factors related to the risk of thrombosis in patients with lupus and antiphospholipid antibodies]. / Factores relacionados con el riesgo de trombosis en pacientes con lupus y positividad para anticuerpos antifosfolipídicos.

BACKGROUND AND OBJECTIVE: Antiphospholipid antibodies (aPL) are frequently associated with eritematosus systemic lupus (SLE) and increases the risk of thrombosis. The aim of the study was to analize risk factors of thrombosis and its temporal profile in subjects with SLE. PATIENTS AND METHOD: One hundred and two SLE patients -mean age: 37.5 years (range: 8-85); 90 women; mean of follow-up: 72 months (range: 9-324); 41 (40.2%) with aPL positive- were included in the study. Actuarial Kaplan-Meier curves were used to assess the thrombosis risk and Cox proportional hazard model was used to evaluate factors associated with the risk. RESULTS: 13 thrombotic events occurred in the group with aPL positive (mean of follow up: 83.5 months) and 5 events in aPL negative group (mean of follow up: 72 months). The event-rates were 3.93 and 0.96/100 patients/year for each group, respectively. Survival curves showed a significantly higher risk of thrombotic events in the patients with positive aPL as compared to the aPL negative group, and the risk still present throughout the observational time. Activated partial thromboplastine time up to 37 s was significantly associated with thrombosis risk (p = 0.003). Furthermore, positivity of lupus anticoagulant and proteinuria > 2.5 g/day tended to increase thrombotic risk, although they did not achieve statistical significance. CONCLUSIONS: In patients with SLE and aPL, risk of first thrombosis remains over the years, and a large activated partial thromboplastine time was the most important risk factor.

Giant mitochondria in the retina cone inner segments of shrews of genus Sorex (Insectivora, Soricidae).

The retinas of three species of shrews (Sorex araneus, S. coronatus, and S. minutus) were analyzed. Two kinds of photoreceptors were identified according to (among other characteristics) the traits of the mitochondria of their inner segments. The rod inner segments contained several round or oval mitochondria distributed longitudinally inside the ellipsoid. The cone inner segment showed a few mitochondria, which we classified as megamitochondria (maximum length = 4.22 microm in S. araneus, 5.68 microm in S. coronatus, and 2.42 microm in S. minutus). An analysis of serial thin sections in S. coronatus showed that these large organelles occurred in the apical and central portions of the ellipsoid. In the peripheral and basal regions of the ellipsoid, megamitochondria were frequently accompanied by smaller mitochondria. The giant mitochondria were irregular in form and densely packed, and a reduced cytosol was observed between each mitochondria. In general, they exhibited an electron-dense matrix and a complex system of cristae, which varied in length and array. In mammalian retina, megamitochondria have only been described in the ellipsoid of the tree shrews Tupaia glis and T. belangeri, two diurnal Scandentia with a rich-cone retina. In general terms, Sorex megamitochondria are morphologically very similar to those reported for Tupaia, especially in their arrangement in the cone ellipsoid. However, they differ in the orientation of the cristae. We propose that the ellipsoid of Sorex may serve two functions: as a source of energy for receptor cells, and as a device for improving the cone outer segment optics.

[Risk factors and clinical characteristics of thromboembolic venous disease in young patients: a prospective study]. / Estudio prospectivo de los factores de riesgo y las características clínicas de la enfermedad tromboembólica en pacientes jóvenes.

BACKGROUND AND OBJECTIVE: We aimed to determine the risk factors of thromboembolic disease in young patients and to study the clinical characteristics according to the etiology. PATIENTS AND METHOD: A prospective study of 100 patients under 50 years who were not affected by neoplasias or chronic diseases and who required hospitalization due to thromboembolic disease. The morphological diagnosis was performed by eco-Doppler, flebography, lung gammagraphy or CT scan. Risk factors assessed were antithrombin, protein C and S deficiency, presence of factor V Leiden, prothrombin G20210A, hyperhomocisteinemia, increased PAI-I, increased factor VIII, and presence of antiphospholipid antibodies (APAs). Acquired factors were also evaluated. RESULTS: In 87% of patients, a venous thrombosis was observed in lower limbs. 37% of patients had congenital risk factors and 19% had APAs, whereas in the remaining patients only acquired factors were demonstrated. Most frequent congenital factors were factor V Leiden, pothrombin G20210A, and protein C and S deficiency. Most patients presented several risk factors. A family thrombotic history was significantly more frequent in the group with congenital risk factors. CONCLUSIONS: In 56% of young patients with thromboembolic disease, a congenital etiology or APAs are identified. In these patients the number of acquired factors needed to trigger thrombosis is fewer than in patients in whom a cause is not identified.

Patient preferences for characteristics of antiretroviral therapies: results from five European countries.

INTRODUCTION: Patient preference to antiretroviral therapy (ART) characteristics should be a key consideration in treatment decisions. ART options exist for people living with HIV (PLWH), however concerns remain related to PLWH satisfaction with current ARTs. The current study examines patient preferences and the strength of preferences for treatment characteristics associated with ART. MATERIALS AND METHODS: Patients' preferences to ART were explored using a discrete choice experiment (DCE). Seven defined treatment characteristics (each with three categories) were identified from a literature review, input from experts, PLWH and physicians. A total of 1582 PLWH from France, Germany, Spain, Italy and the UK were recruited for the study. An adjusted odds ratio <1 signified lower odds of selecting a treatment with this characteristic category, compared to the reference category, independently of other characteristics. RESULTS: The patient preference analyses showed that participants preferred treatments with a rapid reduction in viral load (OR=0.78; 95% CI 0.74-0.81) and CD4 count (OR=0.86; 95% CI=0.82-0.89). Participants had a strong preference for avoiding diarrhoea (Odds ratio, OR=0.36 95% CI=0.33-0.38) and long term health problems (OR=0.30, 95% CI=0.28-0.32). Convenience related issues related to restrictions on taking drugs because of food or drug interactions were important to avoid (OR=0.80, 95% CI=0.76-0.83 and OR=0.72 95% CI=0.69-0.76 respectively). Participants also had a strong preference to avoid drugs which limited the effectiveness of future treatments (OR=0.70, 95% CI=0.67-0.73). CONCLUSIONS: Avoidance of diarrhoea and long-term complications were the most important drivers of patient choice. This study, from a large sample of European patients, demonstrates the importance to patients when different aspects of HIV treatment are considered simultaneously.

Chronic exposure to environmental stressors induces fluctuating asymmetry in shrews inhabiting protected Mediterranean sites.

Many ecotoxicological studies have addressed the effects of contaminant exposure at various levels of biological organization. However, little information exists on the effects of toxicants on wildlife populations. Here we examined exposure of populations of the greater white-toothed shrew Crocidura russula (Soricomorpha, Soricidae) occupying two protected Mediterranean sites (a polluted area, the Ebro Delta, and a control site, Garraf Massif). Bioaccumulation of selected elements (Pb, Hg, Cd, Zn, Cu, Fe, Mn, Cr, Mo, Sr, Ba, and B), a body condition index (BCI) and fluctuating asymmetry (FA) were used to assess the chronic exposure to environmental pollution. BCI was correlated neither to metal concentrations nor to FA, suggesting that this fitness measure only reflects environmental disturbances at a local level. However, shrews from the polluted area showed higher concentrations of metals and metalloids (Pb, Hg, B, and Sr) and greater shape FA than specimens from the reference area. A correlation between FA was found for both first and second principal component vectors suggesting that developmental instability increases as a result of exposure to multiple pollutants. Our results corroborate the suitability of C. russula as a bioindicator of environmental quality and show that FA is an appropriate index to examine impact of developmental stressors in populations inhabiting disturbed areas.

Staggered chromosomal hybrid zones in the house mouse: relevance to reticulate evolution and speciation.

In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed 'zonal raciation'). In this way they can add to the total 'stock' of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event.

Metal and metalloid accumulation in shrews (Soricomorpha, Mammalia) from two protected Mediterranean coastal sites.

Although ecotoxicological data on heavy metals are abundant, information on other potentially toxic elements with attributed deficiency and/or toxic disturbances is scarce. Here we quantify zinc, copper, iron, manganese, chromium, molybdenum, strontium, barium, and boron in bones of greater white-toothed shrews, Crocidura russula, inhabiting two protected Mediterranean coastal sites: the Ebro Delta, a wetland impacted by human activities, and the Medas Islands, a reference site. Natural and anthropogenic inputs significantly increase Fe, Mn, Mo, Sr, Ba, and B in specimens from the Ebro Delta, whereas Cu and Cr were higher in Medas' shrews. Principal component analysis allowed complete separation between sites along the first two axes in particular due to B, Sr, and Cu. This study provides metal reference values in bones of insectivores, explores their variability and bioaccumulation patterns in depth, and assesses the potential environmental risk and toxicity for biota exposed to the above elements.

Cornea, retina, and lens morphology in five Soricidae species (Soricomorpha: Mammalia).

We analyzed the cornea, retina, and lens of five species of Soricidae (pygmy shrew, Sorex minutus; common shrew, Sorex araneus; Millet's shrew, Sorex coronatus; water shrew, Neomys fodiens; greater white-toothed shrew, Crocidura russula) by light and electron microscopy. In all of these species, the corneal epithelium showed a dead cell layer, which may increase the refractive power of the cornea, thereby reducing the hypermetropy that would be expected in a small eye. Moreover, the anterior surface of the lens was more curved than the posterior, thus minimizing spherical aberrations. The thicker lens and its smaller radii of curvature indicated that Sorex species and N. fodiens have a higher refractive lens power than the most nocturnal species, C. russula. In addition, only in the retina cone inner segments of the most diurnal species (genus Sorex) did we find megamitochondria that might act as microlenses to enhance the efficiency of cones. In C. russula, the scarcity of cones and the relatively small yet abundant rod nuclei were found to be consistent with its habits. The flat lens and its more anterior arrangement, together with the lack of megamitochondria in the retina of C. russula, indicated that this species has less visual acuity than the other shrews studied here.

Rb(7.17), a rare Robertsonian fusion in wild populations of the house mouse.

Robertsonian (Rb) translocation is the largest source of chromosomal diversity in the western European house mouse (Mus musculus domesticus). Recently, the fusion Rb(7.17) was found in the chromosomal polymorphic zone of this subspecies in the north-east of the Iberian Peninsula. This fusion has not been reported in any other European population. Here we give data on the distribution and frequency of this mutation in this region. Results revealed that Rb(7.17) is restricted to a small geographic area, and that, in comparison with other fusions in this polymorphic zone, it occurs at low frequencies. We suggest some possible explanations for the distribution of this translocation.

Long-term prospective study of recurrent venous thromboembolism in patients younger than 50 years.

Long-term incidence of recurrent venous thromboembolism (VTE) in patients younger than 50 years, not affected by a malignancy or chronic diseases, are poorly characterized. After the initial episode of VTE and cessation of oral anticoagulation, 98 patients, mean age 32.2+/-9.2 years were followed for a median of 117 months (range 6-165). Congenital risk factors for VTE were present in 36% of patients, acquired persistent (positive antiphospholipid antibodies during the whole follow-up) in 19%, and acquired transitory in 44%. Thirty episodes of recurrent VTE were documented. The cumulative incidence of VTE after 1 year of follow-up was 5.1%, 9.8% after 2 years, 14% after 4 years, and 34.2% after 8 years. In the univariate analysis, the relative risk of recurrent VTE was 2.66 [95% confidence interval (CI) 1.03-6.90] for congenital risk factors, 4.97 (95% CI 1.75-14.0) for persistent acquired (antiphospholipid antibodies), 2.64 (95% CI 1.23-5.66) for male gender and 2.27(1.00-5.15) for body mass index>30 kg/m2. In the multivariate analysis, male gender [hazard ratio (HR) 4.23, 95% CI 1.88-9.77) the presence of congenital factors (HR 3.28, 95% CI 1.25-8.63) and acquired persistent factors (HR 8.50, 95% CI 2.84-25.50) were independent risk factors for recurrent VTE. In patients under 50 years of age without malignancy or underlying chronic disease, hospitalized for an acute thromboembolic event, the presence of antiphospholipid antibodies, congenital defects of coagulation, male sex, and obesity were risk factors for recurrent VTE. These data raise the possibility that selected patients with VTE may require prolonged anticoagulation to prevent recurrent disease.